Electric pulse generator



April 3, 1951 G. H. HOUGH ELECTRIC PULSE GENERATOR Filed Oct. 2, 1948 2 Sheets-Sheet 1 mm mm mm mw av om! om mm R IN V EN TOR. GEO/F65 HUBE/PT HOUGH April 3,1951 G. H. HOUGH 2,547,008

I ELECTRIC PULSE GENERATQR Filed 001". 2, 1948 I 2 Sheets-Sheet 2 IN V EN TOR. 6 5 650/?65 HUM/ 7 HOUGH Patented Apr. 3, 1951 UNITED STATES PATENT OFFICE rmcrarc i i fgi znncaaroa George Hubert Hough, London, England, assignor tolnternational Standard Electric Corporation, New York, .N. Y., a corporation of Delaware Application-October 2, 1948, Serial :No. 52,527

In Great Britain N ovember 13, .1947

.16 Claims. 1

The present invention relates to improve- .ments in .cold cathode gas .filled electric discharge tubes and to electric pulse generating circuits employing such tubes. The principal object of the invention is t provide asequence discharge tube having ,aseries of discharge gaps so disposed that if .one of the gaps be fired, the adjacent gap on one side is caused .to fire after .a certain delay, the gap on the other side being unafiected.

Another object is to apply a tube of this .kind :to the generation of trains of pulses.

The objects .of the invention are achieved by providing a cold cathode gas filled electric discharge tube having a, p1urality of discharge gaps .arranged in sequence, one of the electrodes of one of the .gaps havi l-i. connected thereto an auxiliary electrode arrangednear the corresponding electrode of one of .the other gaps for v the purpose of forming with the said corresponding electrode a triggering discharge gap for the said other gap.

., The invention will .be described with reference to the accompanying drawings in which;

,Fig. 1 shows diagrammatically a cold cathode of pulses and Fig. 2shows a perspective view of an example Fig. 1 of the accompanying drawing shows a I discharge tube according to the invention, with an associated circuit .for enabling it to generate trains of pulses. This tube .is diagrammatically shown and may be constructed in any convenient manner, an example .of which is shown in Fig. 2.

The tube comprises an anode .I which may consist of a .bar or wire with projecting wires orpoints forming a comb. It may alternatively comprisea plain bar or wire or a fiat metal plate;

igelectric discharge tube according to the invention, with an associated circuit adapted to ;generate pulse trains'having a specified number I of the tube diagrammatically shown in Fig. '1.

sponding auxiliary electrodes designated 12 to 2 I (inclusive) are provided. Auxiliary electrodes Nos. l2 to 2B are connected, respectively to the cathodes 3 to H, and their ends are arranged near the ends of the'adjacent cathodes to the or triggering discharge gaps therewith. A further auxiliary electrode 2| not connected to a a cathode is arranged to form an auxiliary gap with the cathode H. It will be noted that the right hand side, Nos. 2 to IQ, forming auxiliary extreme right hand cathode 2 has electrode connected thereto.

The tube may be provided with an additional pair of electrodes .22 and 23 unconnected with the other electrodes, to provide a priming discharge .gap which is intended to be kept per- ,manently discharging for controlling the general level of ionisation in the tube as explained in the specification of co-pending U. S, Application bearing Serial No. 19,084, filed April 5, 1948, by A. Reeves, v now Patent ,No. 2,520,171. This priming gap may be placed in any convenient position with respect to the other electrodes of the .tube and notflnecessarily at the end .of the row, as diagrammaticall shown in the figure; For example, if the electrodes are arranged in a .circle, the priming gap might .be placed .at the centre.

,It shouldbe understood that the priming gap is not essential and could be omitted, but it is very desirable since more stable operation of the tube is secured by its use.

The tube which has been described will be recognised as generally similar to one of those described in thespecification of co-pend'ing U. S. application bearing Serial 'No. 763;655, filed July no auxiliary 255,, .1947, by A. 'Reeves, but the feature which characterises the tube according to the present invention .is the provision of the auxiliary electrodes I? to 2]..

"In order to confine the discharges to the ends of the various electrodes, their surfaces may be covered with alumina or other ,suitable insulating coating except at the tips of the electrodes.

.Any suitable gas filling may be provided for the tube, but a filling comprising 92% neon, 17% hydrogen and 1% argon at a total pressure of 100 him/Hg has been found satisfactory.

'The tube "is shown in Fig. 1, associated with .a circuit for generating trains of pulses con- .ta'iri'ing a desired mm'floer of pulses from one to ten. The anode 1| connected through a resistance '24 to the positive terminal of a high tension operating source 25, the negative terminal of which is connected to ground. The anode ,22 of the priming gap (if provided) :is connected directly to the positive terminal of the source 25, and the cathode 23 of this gap is connected to the negative terminal of a prim 'ing source '26, the positive terminal of which is connected .to ground. Preferably a suitable current limiting resistance {not shown) will be connected in series with one of the electrodes of the "priming gap.

The cathode 2 at the right hand end is connected through a resistance 21 to a common conductor 28 which is connected to ground through the primary winding of an output transformer 29. The remaining cathodes 3 to II are respectively connected to the conductor 28 through resistances 30 to 38 shunted respectively by condensers 39 to ll. The cathodes 3 to H and the auxiliary electrode 2| are respectively connected to corresponding trigger terminals 48 to 51. The secondary winding of the output transformer is connected to a pair of output terminals 58 and 59.

The anode l is also connected to ground through a diode 60 connected in series with a resistance 6|. This diode may be replaced by a germanium or other rectifier, and operates to stabilise the discharges in the manner explained in the specification of co-pending U. S. application bearing Serial No. 19,086, filed April 5, 1948, by A. H. Reeves, since become abandoned.

, The circuit is intended to operate in the following manner.

The potential of the source 25 should be such that it is incapable of initiating a discharge across any gap, but should be sufiicient to maintain any discharge which is struck by any other means. The potential of the source 26 should be such that when added to the potential of the source 25, it is sufiicient to strike andmaintain permanently a discharge between the priming electrodes 22 and 23.

A positive potential of sufiicient magnitude, for

example, in the form of a pulse, is applied to one of the trigger terminals such as 53, for example. The corresponding trigger electrode i'l then acts as an anode in conjunction with the adjacent cathode l and a triggering discharge occurs between these electrodes, causing the main gap between the anode l and the cathode I to be fired. The potential of the electrodes 1 and I6 now rises from zero at a rate determined by the time constant of the resistance 34 and condenser v43 until the trigger electrode l6 reaches a sufliciently high potential to fire the next triggering gap between the electrodes l6 and 6. This fires the main gap between the anode l and the cathode 6, and the process is repeated, the gap between the anode I and the following cathode being ,fired aftera time determined by the time constant of resistance 33 and condenser 82, and so on, until the last gap between the anode l and the cathode 2 is fired. Each time a main gap is fired an increase in current flowing through the primary winding of the transformer 29 occurs,

and the transformer may be designed to differen- ,tiate the leading edges of the current steps so produced, in order to deliver to terminals 58 and Y59 short differential pulses corresponding with these steps.

In order to ensure that triggering only occurs in one direction, asuitably small ratio of the gap distance from a cathode such as 6 to the adjacent'triggering electrode such as IE, to the gap distance from a cathode such as 6 to the adjacent cathode such as I should be used. Alternatively, or in addition, if the tube is required to have very small dimensions, a thin mica sheet (not shown) may be introduced in the gap between any cathode and the trigger electrode connected thereto.

Itshould be noted that when the pulse is applied to terminal 33, the gap between the cathode 8 and the anode I does not fire because the difference of potential across the gap has been reduced by cathodes provided in the tube.

4 the pulse below the maintaining potential for the gap, and as triggering does not occur in the backward direction.

It will be clear that when a positive triggering pulse is applied to terminal 53, exactly six output pulses will be produced; if the triggering pulse is applied to any one of the terminals, 48 to 51, a corresponding number or output pulses from 1 to 10 will be obtained. It is evident also that all gaps once fired will remain discharging and may be extinguished in any convenient Way (not shown) such as by interrupting the connection between the anode l and the resistance 24 or by applying an extinguishing negative pulse of sufficient amplitude to the anode.

The time intervals between successive output pulses are determined by the time constants of the corresponding resistance capacity networks.

and these need not be equal, though it will often be desirable to have these output pulses repeated regularly, in which case all the resistance 30 to 38 and all the condensers 39 to 41 can be equal.

If, for example, it is desired to produce output pulses repeated at the rate or" 2,000 pulses per second, the resistances may each be 50,000 ohms and the capacity of the condensers may be 0.01 micror'arad, assuming a cathode current of 2 milliamperes. The tube in this case would have the gas iilling specified above, the main gap lengths being 1.0 rnm., and the potential of the source 25 being 200 volts. Assuming that the priming gap is of the same length as the others, the voltage of the source 26 could be volts.

The circuit described has several possible applications. For example, it may be used in dialling circuits for producing a train of dialling pulses having any desired number of pulses by applying a single triggering pulse to the appropriate triggering terminal, and these dialling pulses may be given any suitable repetition period by suitably proportioning the resistances and condensers in the cathode circuits.

It is to be noted that it has been found that if the rectifier 6i) and resistance 6| be omitted, the number of gaps which can be discharging at the same time is limited, for example to two. In this case, if a triggering pulse is applied to terminal 51, the cathode ll and ill will be fired in succession, but when the cathode 9 is fired, the source cannot supply enough current to sustain three gaps, and it is found that the first gap is extinguished. When the next cathode 8 is fired, the second gap is extinguished and so on, until at the end or the cycle, the last two stages corre--' sponding to the cathodes 2 and 3 will remain discharging and the process terminates. Another cycle may now be initiated by applying a Iurther triggering pulse to terminal 5i, and this pulse will fire the first gap and extinguish the ninth, and the firing of the gaps in pairs then travels down the tube as before, terminating when the last two gaps are fired. It will be seen that this suggests another application or" the circuit as a frequency multiplier since ten pulses will be obtained from the output transformer 29' for each triggering pulse. It will be clear that the multiplying factor Will depend on the number of Further, with a given number of cathodes various multiplying factors could be obtained by applying the triggering pulses to different ones of the triggering terminals 48 to 5'1.

A further application of this mode or" operating the tube is to the production of trains of time modulated pulses for a multi-channel pulse com- "atria-cos munication system. In this case the cathode 12 is provided with an additional terminal 62..

The circuit operates-by the application of regularly repeated triggering pulses to terminal .5] (Fig. 1), and the modulating speech waves for the respective channels are applied to terminals 62 and 48, to ll. It will be .clear that each time one of the cathodes is fired, .an .output pulse will be obtained from the transformer 29, and the time at which the cathode is fired .and therefore the time of production of the pulse will depend on the instantaneous voltage .of the corresponding signal wave, and which affects the potential of the cathode, since the .adjacent triggering electrode must reach a voltage sufiic'ient to produce the triking difierenceci potential before the triggering gap-can be fired Thus it will be clear that an interleaved train of time modulated channel'pulses will .be obtained from the transformer 29.

It should be added, that if the circuit of Fig. 1 is operated without the rectifier .60 so that only a limited number oi gaps can be discharging at the same time, a continuously repeated cycle of operations may be produced by connecting the cathode ,2 directly to the trigger electrode 2 I, and by shunting the resistance ,2! with a suitable condenser mot shown). Thus it is clear that when the last cathode ,2 is fired, the first one II will be subsequently fired, in the manner already explained, and a new cycle will be commenced. Such cycles are repeated indefinitely, or until the tube is extinguished by some suitable means. The tube thenacts as a generator of cyclically repeated pulses, the pulse intervals being deter- ;mined by the time constants of the resistancefi-pacity circuits.

The pulses in each cycle evidently need not be spaced at equal intervals. ,In the case of a tube operated this way, the cathode and trigger electrode assemblies could, if desired, all be exactly alike and could, be equally spaced around acircle.

Fig. 2 shows to a large scale an example of the manner in which the tube diagrammatically shown in Fig. '1 might be constructed. The envelope 63 is fixed to a conventional base 64 with terminal pins 65. Inside the envelope are two parallel strips of insulating material 66 and 61 supported from the base on suitably bent rods or wires 68 and 69. The lower strip 66 carries 9 equally spaced Y-shaped wire electrodes 10 arranged in a line, each electrode consisting of a straight wire cathode with an inclined branch 1| acting as the trigger electrode, and arranged with its end close to the end of the adjacent cathode. At the left hand end is an L-shaped electrode 12 acting as the trigger electrode for the first cathode, and at the other end is a simple wire cathode 13 without a trigger branch. The electrodes 10, 12, and 73 are each connected to a corresponding one of the base terminal pins 65.

The anode 14 consists of a comb formed by a straight wire 15 having attached thereto wires 16 each of which projects opposite to the corresponding cathode 16 or 73. The anode is connected to a metal boss 11 on the outside of the envelope by a rod 18 which is sealed through the envelope 63 according to conventional practice.

It may be preferable, particularly when a priming gap is used, to arrange the electrodes in a circle or are of a circle (instead of in a straight line as shown in Fig. 2), and the supporting plates 66 and 61 would then take the form of discs. The construction of the tube could, however, be

6 .on quite similar lines, and the anode and cathode of the priming gap inot shown in F g. 2) if pro vided, could be placed at the centres of the slipporting discs, the anode being brou ht outif desired to a separate boss similar to 11.

What is claimed 5:

A gas filled elect on discharge devic omp is n an envel pe encl sin there a an de, a plurality of cathodes Positioned in a sequential series and defining with cooperating anode portions a sequential series of main discharge gaps, a plurality of auxiliary electrodes, and means electrically coupling each auxiliary electrode to a corresponding cathode, each auxiliary electrode having an integral unidirectional proj ecting portion disposed adjacent a succeedi one of said cathodes, each of said auxiliary electrodes -form-- ing with a successive cathode an auxiliary discharge gap.

.2. A gas filled electron discharge device cornprising an envelope enclosing therein a first electrode, a plurality of additional electrodes positioned in a sequential series along a given curve and defining with said first electrode a sequential series of main discharge gaps, at least two of said additional electrodes having .an integral unidirectional projecting portion disposed adjacent a succeeding one of said additional electrodes and defining a triggering discharge gap therebetween operative to initiate the main discharge between said succeeding additional electrode and said first electrode.

.3. A cold cathode gas filled electron discharge device comprising an envelope enclosing therein an anode, a plurality of cathode members mounted in a sequential array and defining with corresponding anode portions a plurality of sequential main discharge gaps, and a plurality of auxiliary electrodes each constituting an integral projection of a corresponding cathode member and having its projecting :outer .end disposed in close adjacency with a succeeding cathode member along said sequential array :to define an auxiliary discharge gap between said auxiliary electrode and its adjacent cathode.

4. A gas filled electron discharge device comprising an envelope enclosing therein an anode, a plurality of cathodes equally spaced from co-- operating anode portions and positioned in :a sequential series, said cathode defining with said cooperating anode portions a sequential series of equally spaced main discharge gaps, a plurality of auxiliary electrodes, andmeans .elec- .trically coupling each auxiliary electrode to, a corresponding cathode, each auxiliary electrode having an integral unidirectional projecting portion disposed adjacent a succeeding one of said cathodes, each of said auxiliary electrodes forming with a successive cathode an auxiliary discharge gap.

5. A cold cathode gas filled electron discharge device comprising an envelope enclosing therein an anode, a plurality of Y-shaped cathode members mounted in a sequential array and one limb of each member defining with corresponding anode portions a plurality of sequential main discharge gaps, the other limb of each member having its projecting outer end disposed in close adjacency with one limb of a succeeding cathode member along said sequential array to define an auxiliary discharge gap between said other limb and th one limbof its adjacent cathode.

6. A device according to claim 1 wherein there is provided an additional pair of electrodes defining a priming discharge gap.

charge device comprising an envelope enclosing therein an anode, a plurality of cathodes positioned in a sequential series, and defining with corresponding anode portions a sequential series "of main discharge gaps, and a plurality of auxiliary electrodes each connected electrically to a corresponding cathode and each having an integral unidirectional projecting portiondisposed adjacent a succeeding one of said cathodes, each of said auxiliary electrodes forming with a successive cathode an auxiliary discharge gap; common conducting means; a plurality of impedancenetworks; connecting means coupling each cathode through a respective one of said networks to said common connecting means; a voltage source connected between said anode and common connecting means and furnishing an operating potential having a value sufficient to maintain a discharge across any anode-cathode gap but insufiicient to initiate such discharge; means for applying a varying triggering voltage to at least one of said auxiliary electrodes; and output voltage deriving means connected in series with at least one of said cathodes.

10. The combination according to claim 9 wherein said means for applying a varying triggering voltage comprises means for applying triggering pulses.

11. In combination, a gas filled electron dis charge device comprising an envelope enclosing therein an anode, a plurality of cathodes positioned in a sequential series and defining with corresponding anode portions a sequential series of discharge gaps, a, plurality of auxiliary electrodes each connected electrically to a corresponding cathode and each having an integral unidirectional projecting portion disposed adjacent a succeeding one of said cathodes, each of i .said auxiliary electrodes forming with a successive cathode an auxiliary discharge gap, and

level within said device; common conducting means; a plurality of impedance networks; coni l conducting means.

necting means coupling. each cathode through a respective one of said networks to saidconimon connecting means, a voltage source connected between said anode and common con necting means and furnishing an operating potential having a valuesufficient to maintain a discharge across any anode-cathode gap but insuflicient to initiate such discharge; means for applying a varying triggering voltage to at least one of said auxiliary electrodes; and output voltage deriving means connected in series with at least one of said cathodes.

12. The combination according to claim 11 wherein each impedance network comprises a resistance shunted by a condenser.

13. The combination according to claim .11 wherein said output deriving means includes an output transformer connected between the negative terminal of said source and said common 14. The combination according to claim 11 wherein there is further provided a stabilising rectifier device connected between said anode and said common conducting means.

15. The combination according to claim 11 wherein said electron discharge device further includes a single triggering electrode positioned adjacent the first cathode in said sequential series, and wherein there is further provided means for applying a triggering voltage to said single triggering electrode, and means for applying a difierent modulating signal to each of said cathodes, said output means comprising riving time modulated pulses.

16. The combination according to claim 11 wherein said electron discharge device further includes an additional pair of electrodes defining a priming discharge gap.

GEORGE HUBERT HOUGH.-

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,230,004 Meikle June 12, 1917 1,647,591 VOOrhiS NOV. 1, 1927 2,011,381 Suits Aug. 13, 1935 2,303,016 B-lount NOV. 24, 1942 2,373,175 Depp Apr. 10,1945 2,408,086 Meacham et a1. Sept. 24,1946 2,443,407

Wales, Jr. June 15, 1948 

